Differential Expression of Neuronal Death-related Factors in Aged Rat Cerebellum

Park, Bum Jun; Chung, Yoon Hee; Kim, Sung Su; Kim, Kyung Yong; Lee, Won Bok

Abstract

In the present study, we investigated the expression of apoptosis-associated proteins in the cerebellum of aged rats: IGF-I receptor (IGF-IR), nitrotyrosine (NT), p53, key pro-apoptotic gene ICH-1 (caspase-2), c-Fos and Bcl-2 family members (Bcl-2 and Bax). Twelve adult (4~6 month old) and 15 aged (24~29 month old) Sprague-Dawley rats were examined in this study. We performed immunohistochemical staining, in situ hybridization and densitometric measurement using a NIH image program (Scion Image) to determine the staining density. In adult rats, there were no immunoreactivities for insulin-like growth factor-I receptor (IGF-IR), nitrotyrosine (NT) or p53 in any region of cerebellum. However, IGF-IR immunoreactivity was found in some Purkinje cells in aged rat cerebellum. The prominent staining of NT or p53 was also localized in the Purkinje cell layer in aged rats. A high density of ICH-1 (caspase-2) immunoreactivity was observed in the molecular and Purkinje cell layers in aged rats. Immunoreactivity for c-Fos was significantly decreased in the granule cells in aged rats. Positive signal for bcl-2 was significantly decreased in the Purkinje cells and granule cells of aged rats. The most intense staining for Bax was observed in the soma of Purkinje cells of adult rats. However, Bax immunoreactivity was not changed in any layers in the cerebellar cortex of aged rats. In conclusion, this study provides the first morphological data concerning the differential regulation of apoptosisrelated genes in rat cerebellum during aging.